A technique disclosed herein relates to drive units configured to drive a movable body using a vibratory actuator.
Conventionally, drive units employing a vibratory actuator have been known. For example, a drive unit according to Japanese Patent Publication No. 2008-172995 drives a movable body by vibrating a vibratory actuator comprised of a piezoelectric element. Specifically, the drive unit is configured so that the movable body is sandwiched between the vibratory actuator and an opposing member arranged at a position which is opposite to the vibratory actuator. The vibratory actuator and the opposing member are biased respectively in directions in which the vibratory actuator and the opposing member press the movable body. Thus, a friction force between the vibratory actuator and the movable body is increased. By vibrating the vibratory actuator in this state, driver elements are displaced according to the vibration of the vibratory actuator, whereby the movable body is driven.
In order to efficiently transmit the driving force of the vibratory actuator to the movable body, a biasing force of the vibratory actuator needs to be increased to increase the friction force between the vibratory actuator and the movable body. However, increasing the biasing force may deform the movable body. Therefore, in the drive unit according to Japanese Patent Publication No. 2008-172995, the rigidity of the movable body is increased. Specifically, members forming the movable body are made of, not a resin material or aluminum alloy, but ceramics or a stainless material having a higher rigidity than resin material or aluminum.